tj-python · pull · May 2, 2026 · May 2, 2026 · May 2, 2026 · May 2, 2026
diff --git a/Doc/c-api/perfmaps.rst b/Doc/c-api/perfmaps.rst
@@ -31,7 +31,7 @@ Note that holding an :term:`attached thread state` is not required for these API
    or ``-2`` on failure to create a lock. Check ``errno`` for more information
    about the cause of a failure.
 
-.. c:function:: int PyUnstable_WritePerfMapEntry(const void *code_addr, unsigned int code_size, const char *entry_name)
+.. c:function:: int PyUnstable_WritePerfMapEntry(const void *code_addr, size_t code_size, const char *entry_name)
 
    Write one single entry to the ``/tmp/perf-$pid.map`` file. This function is
    thread safe. Here is what an example entry looks like::

diff --git a/Doc/deprecations/pending-removal-in-3.20.rst b/Doc/deprecations/pending-removal-in-3.20.rst
@@ -38,3 +38,8 @@ Pending removal in Python 3.20
   - :mod:`zlib`
 
   (Contributed by Hugo van Kemenade and Stan Ulbrych in :gh:`76007`.)
+
+* :mod:`ast`:
+
+  * Creating instances of abstract AST nodes (such as :class:`ast.AST`
+    or :class:`!ast.expr`) is deprecated and will raise an error in Python 3.20.
diff --git a/Doc/library/ast.rst b/Doc/library/ast.rst
@@ -42,7 +42,7 @@ Node classes
 
 .. class:: AST
 
-   This is the base of all AST node classes.  The actual node classes are
+   This is the abstract base of all AST node classes.  The actual node classes are
    derived from the :file:`Parser/Python.asdl` file, which is reproduced
    :ref:`above <abstract-grammar>`.  They are defined in the :mod:`!_ast` C
    module and re-exported in :mod:`!ast`.
@@ -168,6 +168,15 @@ Node classes
    arguments that were set as attributes of the AST node, even if they did not
    match any of the fields of the AST node. These cases now raise a :exc:`TypeError`.
 
+.. deprecated-removed:: next 3.20
+
+    In the :ref:`grammar above <abstract-grammar>`, the AST node classes that
+    correspond to production rules with variants (aka "sums") are abstract
+    classes. Previous versions of Python allowed for the creation of direct
+    instances of these abstract node classes. This behavior is deprecated and
+    will be removed in Python 3.20.
+
+
 .. note::
     The descriptions of the specific node classes displayed here
     were initially adapted from the fantastic `Green Tree
@@ -271,18 +280,25 @@ Root nodes
 Literals
 ^^^^^^^^
 
-.. class:: Constant(value)
+.. class:: Constant(value, kind)
 
    A constant value. The ``value`` attribute of the ``Constant`` literal contains the
    Python object it represents. The values represented can be instances of :class:`str`,
    :class:`bytes`, :class:`int`, :class:`float`, :class:`complex`, and :class:`bool`,
    and the constants :data:`None` and :data:`Ellipsis`.
 
+   The ``kind`` attribute is an optional string. For string literals with a
+   ``u`` prefix, ``kind`` is set to ``'u'``. For all other
+   constants, ``kind`` is ``None``.
+
    .. doctest::
 
         >>> print(ast.dump(ast.parse('123', mode='eval'), indent=4))
         Expression(
             body=Constant(value=123))
+        >>> print(ast.dump(ast.parse("u'hello'", mode='eval'), indent=4))
+        Expression(
+            body=Constant(value='hello', kind='u'))
 
 
 .. class:: FormattedValue(value, conversion, format_spec)
@@ -2536,6 +2552,20 @@ and classes for traversing abstract syntax trees:
       Added the *color* parameter.
 
 
+.. function:: compare(a, b, /, *, compare_attributes=False)
+
+   Recursively compares two ASTs.
+
+   *compare_attributes* affects whether AST attributes are considered
+   in the comparison. If *compare_attributes* is ``False`` (default), then
+   attributes are ignored. Otherwise they must all be equal. This
+   option is useful to check whether the ASTs are structurally equal but
+   differ in whitespace or similar details. Attributes include line numbers
+   and column offsets.
+
+   .. versionadded:: 3.14
+
+
 .. _ast-compiler-flags:
 
 Compiler flags
@@ -2571,20 +2601,6 @@ effects on the compilation of a program:
    .. versionadded:: 3.8
 
 
-.. function:: compare(a, b, /, *, compare_attributes=False)
-
-   Recursively compares two ASTs.
-
-   *compare_attributes* affects whether AST attributes are considered
-   in the comparison. If *compare_attributes* is ``False`` (default), then
-   attributes are ignored. Otherwise they must all be equal. This
-   option is useful to check whether the ASTs are structurally equal but
-   differ in whitespace or similar details. Attributes include line numbers
-   and column offsets.
-
-   .. versionadded:: 3.14
-
-
 .. _ast-cli:
 
 Command-line usage

diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
@@ -1846,6 +1846,13 @@ Deprecated
 New deprecations
 ----------------
 
+* :mod:`ast`
+
+  * Creating instances of abstract AST nodes (such as :class:`ast.AST`
+    or :class:`!ast.expr`) is deprecated and will raise an error in Python 3.20.
+
+    (Contributed by Brian Schubert in :gh:`116021`.)
+
 * :mod:`base64`:
 
   * Accepting the ``+`` and ``/`` characters with an alternative alphabet in

diff --git a/Include/cpython/ceval.h b/Include/cpython/ceval.h
@@ -38,7 +38,7 @@ typedef struct {
 PyAPI_FUNC(int) PyUnstable_PerfMapState_Init(void);
 PyAPI_FUNC(int) PyUnstable_WritePerfMapEntry(
     const void *code_addr,
-    unsigned int code_size,
+    size_t code_size,
     const char *entry_name);
 PyAPI_FUNC(void) PyUnstable_PerfMapState_Fini(void);
 PyAPI_FUNC(int) PyUnstable_CopyPerfMapFile(const char* parent_filename);

diff --git a/Include/internal/pycore_ast_state.h b/Include/internal/pycore_ast_state.h
diff --git a/Include/internal/pycore_ceval.h b/Include/internal/pycore_ceval.h
@@ -94,7 +94,7 @@ typedef struct {
     void* (*init_state)(void);
     // Callback to register every trampoline being created
     void (*write_state)(void* state, const void *code_addr,
-                        unsigned int code_size, PyCodeObject* code);
+                        size_t code_size, PyCodeObject* code);
     // Callback to free the trampoline state
     int (*free_state)(void* state);
 } _PyPerf_Callbacks;
@@ -108,6 +108,10 @@ extern PyStatus _PyPerfTrampoline_AfterFork_Child(void);
 #ifdef PY_HAVE_PERF_TRAMPOLINE
 extern _PyPerf_Callbacks _Py_perfmap_callbacks;
 extern _PyPerf_Callbacks _Py_perfmap_jit_callbacks;
+extern void _PyPerfJit_WriteNamedCode(const void *code_addr,
+                                      size_t code_size,
+                                      const char *entry,
+                                      const char *filename);
 #endif
 
 static inline PyObject*

diff --git a/Include/internal/pycore_debug_offsets.h b/Include/internal/pycore_debug_offsets.h
@@ -215,6 +215,7 @@ typedef struct _Py_DebugOffsets {
         uint64_t state;
         uint64_t length;
         uint64_t asciiobject_size;
+        uint64_t compactunicodeobject_size;
     } unicode_object;
 
     // GC runtime state offset;
@@ -370,6 +371,7 @@ typedef struct _Py_DebugOffsets {
         .state = offsetof(PyUnicodeObject, _base._base.state), \
         .length = offsetof(PyUnicodeObject, _base._base.length), \
         .asciiobject_size = sizeof(PyASCIIObject), \
+        .compactunicodeobject_size = sizeof(PyCompactUnicodeObject), \
     }, \
     .gc = { \
         .size = sizeof(struct _gc_runtime_state), \

diff --git a/Include/internal/pycore_global_objects_fini_generated.h b/Include/internal/pycore_global_objects_fini_generated.h
diff --git a/Include/internal/pycore_global_strings.h b/Include/internal/pycore_global_strings.h
@@ -305,6 +305,7 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(alias)
         STRUCT_FOR_ID(align)
         STRUCT_FOR_ID(all)
+        STRUCT_FOR_ID(all_interpreters)
         STRUCT_FOR_ID(all_threads)
         STRUCT_FOR_ID(allow_code)
         STRUCT_FOR_ID(alphabet)

diff --git a/Include/internal/pycore_interp_structs.h b/Include/internal/pycore_interp_structs.h
@@ -69,7 +69,7 @@ struct code_arena_st;
 struct trampoline_api_st {
     void* (*init_state)(void);
     void (*write_state)(void* state, const void *code_addr,
-                        unsigned int code_size, PyCodeObject* code);
+                        size_t code_size, PyCodeObject* code);
     int (*free_state)(void* state);
     void *state;
     Py_ssize_t code_padding;

diff --git a/Include/internal/pycore_jit.h b/Include/internal/pycore_jit.h
@@ -23,7 +23,7 @@ typedef _Py_CODEUNIT *(*jit_func)(
     _PyStackRef _tos_cache0, _PyStackRef _tos_cache1, _PyStackRef _tos_cache2
 );
 
-_Py_CODEUNIT *_PyJIT(
+_Py_CODEUNIT *_PyJIT_Entry(
     _PyExecutorObject *executor, _PyInterpreterFrame *frame,
     _PyStackRef *stack_pointer, PyThreadState *tstate
 );

diff --git a/Include/internal/pycore_jit_unwind.h b/Include/internal/pycore_jit_unwind.h
@@ -0,0 +1,68 @@
+#ifndef Py_INTERNAL_JIT_UNWIND_H
+#define Py_INTERNAL_JIT_UNWIND_H
+
+#ifndef Py_BUILD_CORE
+#  error "this header requires Py_BUILD_CORE define"
+#endif
+
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(_Py_JIT) && defined(__linux__) && defined(__ELF__)
+#  define PY_HAVE_JIT_GDB_UNWIND
+#endif
+
+#if defined(PY_HAVE_PERF_TRAMPOLINE) || defined(PY_HAVE_JIT_GDB_UNWIND)
+
+#if defined(PY_HAVE_JIT_GDB_UNWIND)
+extern PyMutex _Py_jit_debug_mutex;
+#endif
+
+/* DWARF exception-handling pointer encodings shared by JIT unwind users. */
+enum {
+    DWRF_EH_PE_absptr = 0x00,
+    DWRF_EH_PE_omit = 0xff,
+
+    /* Data type encodings */
+    DWRF_EH_PE_uleb128 = 0x01,
+    DWRF_EH_PE_udata2 = 0x02,
+    DWRF_EH_PE_udata4 = 0x03,
+    DWRF_EH_PE_udata8 = 0x04,
+    DWRF_EH_PE_sleb128 = 0x09,
+    DWRF_EH_PE_sdata2 = 0x0a,
+    DWRF_EH_PE_sdata4 = 0x0b,
+    DWRF_EH_PE_sdata8 = 0x0c,
+    DWRF_EH_PE_signed = 0x08,
+
+    /* Reference type encodings */
+    DWRF_EH_PE_pcrel = 0x10,
+    DWRF_EH_PE_textrel = 0x20,
+    DWRF_EH_PE_datarel = 0x30,
+    DWRF_EH_PE_funcrel = 0x40,
+    DWRF_EH_PE_aligned = 0x50,
+    DWRF_EH_PE_indirect = 0x80
+};
+
+/* Return the size of the generated .eh_frame data for the given encoding. */
+size_t _PyJitUnwind_EhFrameSize(int absolute_addr);
+
+/*
+ * Build DWARF .eh_frame data for JIT code; returns size written or 0 on error.
+ * absolute_addr selects the FDE address encoding:
+ * - 0: PC-relative offsets (perf jitdump synthesized DSO).
+ * - nonzero: absolute addresses (GDB JIT in-memory ELF).
+ */
+size_t _PyJitUnwind_BuildEhFrame(uint8_t *buffer, size_t buffer_size,
+                                 const void *code_addr, size_t code_size,
+                                 int absolute_addr);
+
+void *_PyJitUnwind_GdbRegisterCode(const void *code_addr,
+                                  size_t code_size,
+                                  const char *entry,
+                                  const char *filename);
+
+void _PyJitUnwind_GdbUnregisterCode(void *handle);
+
+#endif  // defined(PY_HAVE_PERF_TRAMPOLINE) || defined(PY_HAVE_JIT_GDB_UNWIND)
+
+#endif  // Py_INTERNAL_JIT_UNWIND_H
diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
diff --git a/Include/internal/pycore_optimizer.h b/Include/internal/pycore_optimizer.h
@@ -198,6 +198,7 @@ typedef struct _PyExecutorObject {
     uint32_t code_size;
     size_t jit_size;
     void *jit_code;
+    void *jit_gdb_handle;
     _PyExitData exits[1];
 } _PyExecutorObject;
 

diff --git a/Include/internal/pycore_runtime_init_generated.h b/Include/internal/pycore_runtime_init_generated.h
diff --git a/Include/internal/pycore_unicodeobject_generated.h b/Include/internal/pycore_unicodeobject_generated.h
diff --git a/Lib/random.py b/Lib/random.py
@@ -836,7 +836,11 @@ def binomialvariate(self, n=1, p=0.5):
             if not c:
                 return x
             while True:
-                y += _floor(_log2(random()) / c) + 1
+                try:
+                    y += _floor(_log2(random()) / c) + 1
+                except ValueError:
+                    # Reject case where random() returned 0.0
+                    continue
                 if y > n:
                     return x
                 x += 1